美国俄亥俄大学Patrick M. O’Connor，Christopher R. Torres和美国德克萨斯大学奥斯汀分校Julia A. Clarke共同合作，近期取得重要工作进展。他们通过研究白垩纪南极鸟类头骨揭示了早期鸟类生态多样性。相关研究成果2025年2月5日在线发表于《自然》杂志上。

据介绍，代表白垩纪冠群鸟类（Aves）谱系的化石极为罕见，但这些化石对于阐明早期鸟类分化过程中的主要生态转变至关重要。已知最早的冠群鸟类之一是Vegavis iaai，这是一种来自南极洲晚白垩世（约6920万至6840万年前）的蹼足潜水鸟类，其系统发育关系存在争议。最初通过系统发育分析被归类为雁形目（鸭类及其近缘物种）的基干类群，但后来又被认为是雁形目（水禽）的基干成员，甚至认为它完全不属于鸟纲。

研究人员发现了一件新的、近乎完整的Vegavis头骨化石，为研究其摄食生态提供了新的见解，并展示了支持其归属于冠群鸟类中雁形目的形态特征。

Vegavis具有典型的鸟类喙部特征（无牙齿和退化的上颌骨）以及脑部形态（高度膨大的大脑和腹侧移位的视叶）。其颞窝深且宽阔，表明这种鸟类具有高度发达的颌部肌肉。喙部狭窄且尖，下颌骨缺乏后关节突。这些特征共同构成了一种与任何其他已知雁形目鸟类不同的摄食器官，但与现存的某些水下捕食鸟类（如??和潜鸟）相似。Vegavis在白垩纪的出现及其独特的摄食生态（在已知的鸡雁总目，即水禽和陆禽中独一无二），这进一步表明，最早的雁形目分化具有演化试验性，在现存物种多样性中并无体现。

附：英文原文

Title: Cretaceous Antarctic bird skull elucidates early avian ecological diversity

Author: Torres, Christopher R., Clarke, Julia A., Groenke, Joseph R., Lamanna, Matthew C., MacPhee, Ross D. E., Musser, Grace M., Roberts, Eric M., OConnor, Patrick M.

Issue&Volume: 2025-02-05

Abstract: Fossils representing Cretaceous lineages of crown clade birds (Aves) are exceptionally rare but are crucial to elucidating major ecological shifts across early avian divergences. Among the earliest known putative crown birds is Vegavis iaai1,2,3,4,5, a foot-propelled diver from the latest Cretaceous (69.2–68.4million years ago)6 of Antarctica with controversial phylogenetic affinities2,7,8,9,10. Initially recovered by phylogenetic analyses as a stem anatid (ducks and closely related species)1,2,11, Vegavis has since been recovered as a stem member of Anseriformes (waterfowl)7,8,9, or outside Aves altogether10. Here we report a new, nearly complete skull of Vegavis that provides new insight into its feeding ecology and exhibits morphologies that support placement among waterfowl within crown-group birds. Vegavis has an avian beak (absence of teeth and reduced maxilla) and brain shape (hyperinflated cerebrum and ventrally shifted optic lobes). The temporal fossa is well excavated and expansive, indicating that this bird had hypertrophied jaw musculature. The beak is narrow and pointed, and the mandible lacks retroarticular processes. Together, these features comprise a feeding apparatus unlike that of any other known anseriform but like that of other extant birds that capture prey underwater (for example, grebes and loons). The Cretaceous occurrence of Vegavis, with a feeding ecology unique among known Galloanserae (waterfowl and landfowl), is further indication that the earliest anseriform divergences were marked by evolutionary experiments unrepresented in the extant diversity3,11,12,13.

DOI: 10.1038/s41586-024-08390-0

Source: https://www.nature.com/articles/s41586-024-08390-0